1. Field of the Invention
The present invention relates to a power supply device and a storage control device.
2. Description of the Related Art
The storage control device comprises a storage section in which a multiplicity of hard disk drives are connected in the form of an array and provides a host computer (‘host’ hereinbelow) such as a server with logical storage regions (logical volumes).
In order to increase reliability and highly availability, the storage control device provides the host with storage regions that are redundant based on RAID (Redundant Array of Independent Disks). Further, the storage control device affords the various resources such as the microprocessor and communication path redundancy. From the perspective of such high reliability and high availability, the power supply device of the storage control device is also made redundant.
Therefore, according to a first conventional technology, a DC/DC converter is installed in each of the hard disk drives (Japanese Application Laid Open No. 2004-126972). As a result, according to the first technology, even when power fault occurs within any one hard disk drive, the power fault prevents an adverse effect on the other hard disk drives.
According to a second conventional technology, a plurality of hard disk drives are constituted as one group and a plurality of DC/DC converters are assigned to each group (Japanese Application Laid Open No. H11-168832). According to the second conventional technology, power is normally supplied to the respective hard disk drives by one DC/DC converter. According to the second conventional technology, when a fault occurs in one DC/DC converter, there is an automatic switch from one DC/DC converter to another DC/DC converter and power is supplied by the other DC/DC converter to the respective hard disk drives.
According to the first conventional technology of Japanese Application Laid Open No. 2004-126972, because a DC/DC converter is installed in each hard disk drive, each DC/DC converter must be able to output balanced power at the level of the maximum power consumed by the respective hard disk drives. Hence, DC/DC converters with an adequate output performance must be prepared in a number equal to the total number of hard disk drives and the costs of power supply devices increase. Furthermore, because there is a need to prepare DC/DC converters of the same number as that of hard disk drives, there is an increase in the number of parts and the stockpile number, whereby the productivity of the power supply device is reduced.
According to the first conventional technology, because the output capacities of the respective DC/DC converters are established in accordance with the maximum power consumption of the respective hard disk drives, the output capacity of an AC/DC converter for supplying DC power to the respective DC/DC converters must be large. As a result, the costs of the power supply device increase and the device size also increases.
Furthermore, according to the first conventional technology, because the respective hard disk drives individually contain a DC/DC converter, when a power fault occurs in the DC/DC converter, the respective hard disk drives cannot be operated.
In addition, according to the first conventional technology, each of the hard disk drives comprises only one DC/DC converter and the DC/DC converters do not have a redundant configuration. Hence, the DC/DC converter alone cannot be exchanged.
Furthermore, with the first conventional technology, when power fault has occurred, it is not possible to specify whether a fault of the DC/DC converter is the cause or whether the occurrence of a fault in another circuit in the hard disk drive is the cause of the power fault. Therefore, for the hard disk drive in which the power fault occurred, the whole of the hard disk drive must be exchanged.
According to the second conventional technology, because a plurality of DC/DC converters are provided in group units, it is possible to reduce the number of DC/DC converters in comparison with the first conventional technology. However, with the second conventional technology, because it is necessary to prepare a first DC/DC converter and a second DC/DC converter for each group, the costs of the power supply device increase. According to the second conventional technology, normally power is supplied by only the first DC/DC converter to each of the hard disk drives while the second DC/DC converter remains on standby. Hence, according to the second conventional technology, there is a large number of DC/DC converters that are normally not used and the costs increase. Further, because the space of the storage control device is then small to the extent that a DC/DC converter that is not normally used is installed, it is hard to install a multiplicity of hard disk drives in the storage control device.